G-17 Differences in background data system boundaries

Aspect G-17 Differences in background data system boundaries
Currently, practitioners have to deal with various different data sources, such as public or commercial LCI databases, EPDs, literature, etc. All these data have been calculated by applying different rules, and so special attention has to be paid to assessing the consistency of these different sources. An increasing number of EPDs for building products are freely available in the market. These EPDs have been produced in the framework of different programmes, applying different product category rules (PCR) and system boundaries, and so they should not be directly compared nor combined. Recently, the EN 15804 standard has been approved, and in the coming years will foster harmonization between the various EPD programmes. In the meantime, how can the practitioner deal with differing background data?

related study objective

stand-alone LCA comparative assertion

related study phase

goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for

new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions An increasing number of EPDs for building products are available. These EPDs apply different system boundaries, e.g. cradle to gate (product stage), cradle to grave (the whole life cycle) and cradle to gate with options (Modules A1–A3 plus other, additional modules). If the EPD is EN 15804 compliant, then the information is declared separately for each module, facilitating its use in building LCA studies. EPDs that comply with EN 15804 should also provide additional technical information to ensure proper understanding of a product’s function in a building by supporting scenario development at the building level.For all these reasons, EN 15804-compliant EPDs can be accepted as a data source for building LCA as well as generic data (if the goal is to do e.g. a screening LCA). These EPD data may also be seen as an appropriate data source for background data as well as the usual generic data.
Rules from:
EN 15804
5.2 Types of EPD with respect to life cycle stages covered
EN 15978
10 Selection of environmental data and other information – Use of Environmental Product Declaration(s)
Different EPDs and other background data may be used for a building LCA study; however, special care has to be taken when using these different data sources for building LCA. In this sense, it is key to have a good understanding of whether the LCA-based information found in an EPD represents the product stage only (e.g. cradle to gate), the product stage and selected further life cycle stages (cradle to gate with options EPD) or the complete life cycle of the product (cradle to grave). Additional technical information included in the product’s EPD (such as service life, transportation distance, loss of the product on-site, etc.) would also be very useful for the assessment at the building level. In any case, consistency of the LCA modelling should be ensured so that the system boundary of the EPDs is homogeneous.Whenever possible, the use of EPDs that comply with EN 15804 should prevail, if they are more relevant for use in a national context than any other background data. In addition, the practitioner should check that the LCA-based information found in such EPDs is compatible with the scope of the study.In addition to such EN 15804-compliant EPDs, the practitioner most likely has to rely on various background data sources, such as public or commercial databases. It is strongly recommended that practitioners use as much data as possible from a consistent source (e.g. one public national database), which ideally should be methodologically consistent with the appropriate EPDs (e.g. from one national EPD programme with the same methodological assumptions). If EPD data are to be used as background data, it is important to ensure that they can be reused for further EPD – e.g. a raw material EPD used for a product EPD. In this context, it is important to have a data-compatible exchange format to ease the use of EPD (the information to be reused is likely to be only the cumulative impact results, as no LCI is provided in most EPD programmes).

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